Review of design methods and ferm analysis of unpaved roads reinforced with geosynthetics

The geosynthetics are widely used in mechanically stabilization of unpaved roads with a low volume of traffic. The practical use of geosynthetics above a weak subgrade or within a base course has demonstrated the benefit of reducing rut depths and prolonging pavement life. Alternatively, for the same traffic conditions and allowable rut depth, the use of geogrid reinforcement allows a reduction of the construction cost by decreasing the base layer thickness in comparison with the thickness required when the base layer is unreinforced (if the cost of the geosynthetic reinforcement is less than the cost of the base material). The main purpose of this study is to analyze design criteria currently available for reinforced unpaved roads comparing the results obtained by different design procedures aimed at estimating the base thickness required for reinforced unpaved roads, underlining their improvements and limits. Furthermore, a parametric analysis varying design parameters such as soils and geosynthetics mechanical properties, allowable rut depth and traffic conditions, has been conducted. Moreover, to predict the behavior of unpaved roads, both in unreinforced system and reinforced with geosynthetics configuration, a finite element models have been implemented in ABAQUS program. The focus of this approach is to assess the geogrid reinforcement contribution to reduce the rut depth under repeated wheel traffic load conditions.